WO1994024484A1 - Method of reducing the emissions produced by incinerating waste - Google Patents
Method of reducing the emissions produced by incinerating waste Download PDFInfo
- Publication number
- WO1994024484A1 WO1994024484A1 PCT/EP1994/001101 EP9401101W WO9424484A1 WO 1994024484 A1 WO1994024484 A1 WO 1994024484A1 EP 9401101 W EP9401101 W EP 9401101W WO 9424484 A1 WO9424484 A1 WO 9424484A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- flue gas
- combustion
- waste
- oxygen
- cleaning system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/006—General arrangement of incineration plant, e.g. flow sheets
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
- F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
- F23G5/14—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion
- F23G5/16—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion in a separate combustion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/20—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having rotating or oscillating drums
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
- F27B7/20—Details, accessories or equipment specially adapted for rotary-drum furnaces
- F27B7/22—Rotary drums; Supports therefor
- F27B7/24—Seals between rotary and stationary parts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2202/00—Combustion
- F23G2202/10—Combustion in two or more stages
- F23G2202/103—Combustion in two or more stages in separate chambers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2203/00—Furnace arrangements
- F23G2203/20—Rotary drum furnace
- F23G2203/212—Sealing arrangements between rotary and stationary parts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L2900/00—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber
- F23L2900/07001—Injecting synthetic air, i.e. a combustion supporting mixture made of pure oxygen and an inert gas, e.g. nitrogen or recycled fumes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L2900/00—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber
- F23L2900/07007—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber using specific ranges of oxygen percentage
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/32—Direct CO2 mitigation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Definitions
- the invention relates to a method for reducing the emissions from the incineration of waste in an incineration plant, in which part of the flue gas produced during the combustion is recirculated, the recirculated flue gas is admixed with the oxygen required for combustion, and one in a flue gas purification plant Flue gas cleaning takes place.
- the primary measures i.e. Measures to avoid pollutant formation, more and more important. These consist e.g. in avoiding dust formation in the combustion process and in reducing sulfur-containing pollutants when selecting the fuels.
- the further development of the primary measures is also important because the denitrification of flue gases by catalytic reduction with ammonia gas is carried out at high temperatures (200 to 250 ° C) and after desulfurization and dedusting to protect the catalyst. For this purpose, the flue gas cooled in the desulfurization system has to be heated up again with a high energy requirement.
- the object of the invention is therefore a method and a device for reducing the emissions from the incineration of waste. to create, in which the emissions in the exhaust air entering the atmosphere are further reduced.
- conventional rotary tube systems can be used, ie the use of pure oxygen should not result in temperatures that are incompatible with the existing design of these systems.
- the formation of emissions, especially nitrogen oxides should be drastically reduced. This should also be achieved in such a way that existing systems can be converted.
- the solution to this problem is, according to the invention, that the return of the flue gas to the entrance of the incinerator takes place as a continuous cycle, that the flue gas cleaning system is designed in two stages and that the flue gas is returned after cleaning in the first stage of the flue gas cleaning system and that the ratio of flue gas and oxygen in the synthetic air added at the front of the incinerator, which is formed by mixing flue gas and pure oxygen, is 4: 1 to 1: 1, preferably in the ratio 1.5: 1 to 2: 1.
- the process according to the invention drastically reduces the proportion of nitrogen oxides in the flue gas which is attributable to the thermal NO ⁇ formation in conventional systems which work with air, and possibly reduced to zero.
- the total nitrogen oxide content of the flue gas can thus be reduced to such an extent that a denitrification system is no longer necessary because the legally prescribed limit values are undershot from the outset.
- the method according to the invention and a device operating according to it not only reduce the emission of nitrogen oxides, but overall the emission of all emissions, since a high proportion of the flue gas and thus a correspondingly high proportion of the pollutants produced during combustion do not enter the atmosphere, but gets into the flue gas recirculation and thus remains in the flue gas circuit. It is therefore a special feature of the method that, overall - based on a certain volume of waste to be incinerated - only part of the exhaust gas, namely as far as it is not recycled, is released into the atmosphere. So only the amount of flue gas reaches the chimney that arises from the oxidation of the hazardous waste by the oxygen contained in the combustion gas. The remaining amount of flue gas circulates continuously. This has the additional advantage that all pollutants are reduced by up to 80%. So at the same time the nitrogen oxide quantities are drastically reduced and the flue gas volume that leaves the system is reduced by up to 80%.
- the steam production is approx. 24 t / h, if approx. 4 t / h waste with an average calorific value of 15 MJ / kg burns.
- the steam is generated at a pressure of approx. 32 bar and at a temperature of approx. 350 ° C.
- the excess gas is a quantity of not more than 6000-7000 Nm 3 / h through the chimney into the environment. Due to the high volumetric heat capacity of the C0 2 -rich combustion gas, the heat flow densities can be increased from 150 KW / m 3 to 200-300 KW / m 3 depending on the design of the rotary tube.
- a further feature of the invention is to provide the first stage of the flue gas cleaning system within the circuit, which is in particular set up (cf. claim 9) that the flue gas is dust, chlorine , Heavy metals and sulfur dioxide are removed.
- the second stage of the flue gas cleaning system through which the part of flue gas that does not go back into the circuit passes, then serves to purify dioxins, furans, and also to purify sulfur dioxide, heavy metals and - if necessary at all - nitrogen oxides (claim 10 ).
- This division of the flue gas cleaning system into two stages and the inclusion of the first stage in the continuous flue gas circuit has the result that an accumulation of pollutants in the circuit is avoided.
- the requirements for this first stage of the flue gas cleaning system are not very strict in this respect, since the "rest" of the flue gas leaving the first stage, which is discharged into the atmosphere, is completely cleaned down to the critical limit values in the second stage, if necessary.
- the ratio of flue gas (C0 a ) to oxygen is 4: 1 to 1: 1.
- a particularly preferred range is 2: 1 to 1.5: 1.
- the proportions are used to influence the flame temperature in adaptation to the different materials that are burned as well as to optimize the entire combustion process.
- An advantageous development of the invention provides that the combustion process is controlled by adding fluid support energy sources (claim 2), in particular by purified pyrolysis gas and pyrolysis oil, which are produced in an upstream pyrolysis (claim 6).
- the upstream pyrolysis removes portions of high-calorific waste from the hazardous waste before incineration. This reduces the flue gas volume.
- Another advantage is that dangerous toxins such as PCB, dioxins, furans, etc. and nitrogenous substances are destroyed. In this way, the NO x formation is reduced even further.
- the oxygen is advantageously generated in an air separation plant with the aid of the process energy obtained in the combustion (claim 3).
- air separation in addition to oxygen, essentially nitrogen is also obtained, which can serve as a protective gas in the comminution of the special waste prior to combustion or pyrolysis (claim 5).
- the combustion air is normally based on a composition of 75% by volume nitrogen, 13.3% by volume oxygen and 11.7% by volume H 2 0, the density of the components at 1000 ° C. also being used assumes a volume-specific heat capacity of 0.36 kJ / m 3 .k. If one bases the “synthetic air” according to the invention on 75 volume percent CO 2 , 13.3 volume percent 0 2 and 11.7 volume percent H 2 0, this results in a volume-specific heat capacity of 0 , 53 kJ / m 3 .k. With the same volume throughputs, the heat transport in otherwise identical conditions is 47% better for synthetic air than for normal air.
- the Prandtl number for air and synthetic air is less than 1, ie the spatial extent of the thermal boundary layer is greater than that of the aerodynamic boundary layer, which suggests a comparable heat transfer for both gas mixtures, e.g. boiler heat transfer surfaces.
- the difference shown in the heat capacity and the increased heat capacity of the synthetic air has the consequence that the combustion output can be increased 1.5 times with the otherwise identical design of a system. So if you retrofit existing systems according to the invention, you can increase the power release at the same time. This is another very important advantage of the invention. If it turns out that the heat transfer due to the "normal" dimensioning of the heat transfer surface on the boiler is too small, the heat transfer surface can be easily increased. This increase in heat throughput also changes the flow rate compared to conventional driving. By regulating the flow rate, a stable flame on the burner and thus a stable combustion process is ensured. For this purpose, an advantageous development of the invention provides that control devices are arranged in the line for returning the cleaned flue gas.
- FIG. 1 shows the process flow
- FIG. 2 shows a detail of the sealing device 45 at the front end 1 a of the rotary tube 1, which is indicated only schematically in FIG. 1.
- a controllable energy source ie a fluid fuel
- It can be fossil Earth energy sources, such as oil or gas.
- Products of an upstream pyrolysis 3 are used.
- high-calorific waste i.e. with an energy content of more than 25 J / kg
- waste plastics or car tires are pyrolyzed at 480 to 700 ° C .
- the cleaned pyrolysis gas and / or the pyrolysis oil are fed into line 2.
- the amount of pyrolyzable waste should be at least 40 to 50% of the amount of hazardous waste.
- the combustion of the entire system is energy self-sufficient.
- the fuel line 2 branches into a line 2a, which leads to a burner 4a at the front end la of the rotary tube 1, and a line 2b, which leads to a burner 4b in an afterburning chamber 5.
- the burner 4a is supplied via line 7 with synthetic air via a line 6, which opens into the front end 1 a of the rotary tube 1.
- the synthetic air is generated in a mixing chamber 21 which, on the one hand, is supplied with flue gas, ie essentially C0 2 , via line 20 and, on the other hand, oxygen which is produced in an air separation plant 23.
- This synthetic air is fed to the front end la in the flow direction in the vicinity of the burner 4a to the rear end lb of the rotary tube l.
- the waste is thus incinerated, which is quasi continuously added to the rotary tube 1 via a high-pressure line 60 by pumping.
- the hazardous waste is burned in the rotary tube 1 and moves from a low temperature area of approx. 400 up to 700 ° C at the front end la up to a higher temperature range of approx. 1200 to 1300 ° C at the rear end lb. Subsequently, the flue gas generated during the combustion passes into the afterburning chamber 5 already mentioned, in which the burner 4b is arranged, to which the synthetic air is fed via line 8 and a fluid fuel via line 2b. Afterburning takes place in the afterburning chamber 5. The burned-out molten slag is drawn off at exit 10 and quenched in a water bath.
- the flue gas passes from the afterburning chamber 5 into a radiation part 11, where it is cooled and from there into a waste heat boiler 12 with a convection heat exchanger 13.
- the flue gas is used with further cooling to generate steam which is used to generate electricity (not shown here) .
- the cooled flue gas which still has a temperature of approximately 300 to 400 ° C., then passes into a two-stage flue gas cleaning system, the first stage of which is designated by 14 and the second stage is designated by 24.
- the first stage 14 of the flue gas cleaning system dust, chlorine compounds (especially HC1), sulfur dioxide and heavy metals are separated.
- the first stage 14 can be designed as a sequence of individual sections which are assigned to the individual cleaning tasks. This is known to the person skilled in the art. It is therefore not explained in detail in the following context.
- the flue gas cleaned in the first stage 14 of the flue gas cleaning system is returned to a part that is set with the control flap 61 via the line 20, wherein, as already mentioned, pure oxygen is mixed in to the mixing chamber 21 in order to to obtain synthetic air required for combustion in the rotary tube 1.
- the proportion of returned flue gas corresponds to the proportion of nitrogen in normal air (4: 1). However, it can be selected lower in order to generate an air ratio lambda greater than 1 in order to thereby set optimal operating conditions.
- the setting is carried out such that the ratio of flue gas to oxygen behind the mixing chamber 21 in the lines 6, 7, 8 fluctuates between 4: 1 and 1: 1. It is preferably in the range 2: 1 to 1.5: 1.
- This constant cleaning of the flue gas in the circuit has the result that the proportion of harmful exhaust gases in the part of the flue gas that finally comes out via the line 19 and then after the second stage 24 of the flue gas cleaning system via the chimney 27, compared to conventional ones Systems are therefore considerable is reduced because overall the part of the flue gas released into the atmosphere is much lower than in conventional systems.
- the amount of flue gas can be reduced from about 7.5 x 10 3 m 3 per ton in known processes to about 1.5 x 10 3 m 3 per ton of special waste.
- the part of the flue gas that is not returned to the continuous flue gas circuit in line 20 passes via line 19 to the second stage 24, in which the residual purification of the flue gas takes place, in particular with regard to residual sulfur dioxide and residual heavy metals. There is also the cleaning of dioxins and furans in corresponding
- Separation devices are provided. Possibly. can, if necessary, also a residual cleaning of. Nitrogen oxides occur if they are nevertheless formed because natural air is drawn in through leaks in the entire system or because nitrogen compounds were contained in the waste that is incinerated.
- combustion capacity of such a system is increased by approximately 1.5 times as a result of the higher thermal capacity of the synthetic air compared to conventional systems.
- This increase in combustion performance also leads - in relation to the dimensions of conventionally designed combustion plants - to a changed flow rate, which may Tearing down the flame of the burner 4a can serve. This can be countered by regulating the flow rate in the lines 6, 7, 8.
- Control devices 40, 41, 42 are provided there for this purpose.
- the seals of the rotary tube 1 are provided with chambers 45 at the front end 1 a and 46 at the rear end 1 b, which are connected via the lines 51 , 52 flue gas is also supplied.
- This flue gas serves as a protective gas for the seals and prevents the intake of normal nitrogen-containing air.
- the pure oxygen which is fed to the mixing chamber 21 via the line 22, is obtained in an air separation plant 23.
- the nitrogen produced in the air separation plant 23 can again serve as protective gas, both on the one hand - this would be a modification of the exemplary embodiment shown in the drawing - with regard to the seal of the rotary tube system, but also in the shredding plant (not shown) in which the hazardous waste is preconditioned and being prepared for combustion.
- the protective gas is used to suppress the formation of explosive mixtures.
- FIG. 2 shows a detailed design of the sealing device 45 at the front end 1 a of the rotary tube 1.
- the rotary tube 1 is provided with two flanges 62 and 63, to which rings 64 and 65 are screwed. The screw connection is indicated by the dash-dotted lines.
- the rings 64, 65 are divided for reasons of assembly.
- the rotary tube 1 is surrounded by a stationary ring section 66, in which the line 67, via the Flue gas is supplied, flows.
- the line 67 in FIG. 2 has the same function as the line 51 in FIG. 1.
- On the ring section 66 there are two sealing support rings 68, 69 which are U-shaped in cross section and each have rectangular recesses 70, 71 in cross section, which the rings 64, 65 surrounded.
- Sealing rings 72, 73 and 74, 75 are accommodated in the side surfaces of the recesses 70, 71. They are pressed by groups of springs 76, 77, 78, 79 against rings 64, 65 which rotate with the rotary tube 1 and thus form a mechanical seal. Further flanges 80, 81 are welded to the seal support rings 68, 69.
- the seals are known as "Burgmann seals".
- a compensator 82 adjoins the two Burgmann seals to the left in FIG.
- the compensator 82 is welded to the box 83, which forms the end wall of the rotary kiln.
- the compensator consists of two ring sections 84, 85, two rings 86, 87 perpendicular to the axis of the rotary tube and a U-shaped compensation part 88.
- the ring section 85 is welded to the seal support ring 68 on the inside.
- the compensator 82 is used to compensate for changes in length due to the heating.
- a pressure of approx. Minus 4 - 5 mbar prevails in the front (in Figure 2: left) end of the rotary tube. Since the pressure outside the rotary tube is, for example, 1000 mbar, there is a considerable pressure difference between the outside and inside. Without special measures, it would lead to atmospheric air being drawn into the rotary tube 1 along the dash-dotted line L. This would have the effect that the nitrogen contained in the drawn-in false air can form nitrogen oxides in the rotary tube. To avoid this, it is provided that, as mentioned, flue gas via line 67, specifically is also supplied at a pressure of 1000 mbar. The flue gas then fills the spaces 89 and 90.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Incineration Of Waste (AREA)
- Gasification And Melting Of Waste (AREA)
- Treating Waste Gases (AREA)
Abstract
Description
Titel: Verfahren zur Reduzierung der Emissionen bei der Verbrennung von AbfällenTitle: Process for reducing emissions from waste incineration
Beschreibungdescription
Die Erfindung betrifft ein Verfahren zur Reduzierung der Emissionen bei der Verbrennung von Abfällen in einer Verbrennungsanlage, bei dem ein Teil des bei der« Verbrennung entstehenden Rauchgases zurückgeführt, dem zurückgeführten Rauchgas der zur Verbrennung erforderliche Sauerstoff zugemischt wird und bei der in einer Rauchgas-Reinigungsanlage eine Rauchgasreinigung erfolgt.The invention relates to a method for reducing the emissions from the incineration of waste in an incineration plant, in which part of the flue gas produced during the combustion is recirculated, the recirculated flue gas is admixed with the oxygen required for combustion, and one in a flue gas purification plant Flue gas cleaning takes place.
Ein derartiges Verfahren ist aus der DE 40 26.245 AI bekannt geworden. Dieses Verfahren geht im Prinzip davon aus, zur Verbrennung "reinen Sauerstoff ohne Verdünnung" einzusetzen (siehe Sp. 1, Z. 58; Sp. 3, Z. 47/48, sowie Anspruch 1), um eine erhebliche Reduktion des Volumens, auf das die Anlage ausgelegt werden muß, zu erreichen, erwähnt aber, daß "zur Vermeidung von Überhitzungen" und bei Bedarf abgekühltes Abgas wieder in die Verbrennungskammer zurückgeführt wird und damit der Sauerstoff verdünnt wird (Sp. 2, Z. 43/44 und 50/51). Es ist auch ausgeführt, daß die Verwendung reinen Sauerstoffs, mit oder ohne Verdünnung, die Bildung von Stickoxiden und anderen Emissionen verhindert (Sp. 1, Z. 51/52 und Sp. 2, Z. 9/10). Wegen der Angabe in dieser Veröffentlichung, daß die Abgasrückführung nur "bei Bedarf" und zur Vermeidung einer Überhitzung der Anlage erfolgen soll, jedoch andererseits, daß durch Verwendung reinen Sauerstoffs "ohne Ballast" eine Verkleinerung der Anlage angestrebt wird, ist davon auszugehen, daß die Beimischung von rückgeführtem Rauchgas nur in geringem Umfang und nicht dauernd erfolgt. Das folgt auch daraus, daß die in dieser Druckschrift genannten Temperaturen von 1600°C (Sp. 4, Z. 57) relativ hoch sind.Such a method has become known from DE 40 26.245 AI. In principle, this method assumes that "pure oxygen without dilution" is used for the combustion (see column 1, line 58; column 3, line 47/48, and claim 1) in order to reduce the volume considerably, to which the system must be designed to achieve, but mentions that "to avoid overheating" and, if necessary, cooled exhaust gas is returned to the combustion chamber and thus the oxygen is diluted (Col. 2, lines 43/44 and 50 / 51). It is also stated that the use of pure oxygen, with or without dilution, prevents the formation of nitrogen oxides and other emissions (column 1, line 51/52 and column 2, line 9/10). Because of the information in this publication that the exhaust gas recirculation should only take place "when required" and to avoid overheating of the system, but on the other hand that the use of pure oxygen "without ballast" is intended to reduce the size of the system, it can be assumed that the Recycle flue gas is added only to a small extent and not continuously. This also follows from the fact that the temperatures of 1600 ° C. (column 4, line 57) mentioned in this publication are relatively high.
Nachteilig bei dem bekannten Verfahren ist, sofern je ein Kreislauf und/oder eine Rückführung eines nicht unerheblichen Teils des Abgases erfolgen sollte, daß in dem Kreislauf eine Anreicherung der bei der Verbrennung im Drehrohr entstehenden Schadstoffe erfolgt, die eine Korrosion der Anlage zur Folge haben kann und auch eine größere Auslegung der nachgeschalteten Rauchgas- Reinigungsanlage erforderlich macht. Schließlich bedingt, wie oben schon angedeutet, die Verwendung reinen Sauerstoffs, auch bei Beimischung gekühlten Rauchgases "bei Bedarf", eine erhöhte Temperatur im Drehrohr und eignet sich daher nicht für die Umrüstung bestehender an sich mit atmosphärischer Luft arbeitender Verbrennungsanlagen.A disadvantage of the known method, if a cycle and / or a recirculation of a not inconsiderable part of the exhaust gas should take place, is that in the circuit there is an accumulation of the pollutants that arise during combustion in the rotary tube, which can result in corrosion of the system and also requires a larger design of the downstream flue gas cleaning system. Finally, as already indicated above, the use of pure oxygen, even when admixed with cooled flue gas "when required", results in an increased temperature in the rotary tube and is therefore not suitable for retrofitting existing combustion plants which work with atmospheric air.
Ganz allgemein ist es bei der Verbrennung von Abfällen (Hausmüll oder Sonderabfälle) von großer Bedeutung, daß die Schadstoffanteile im Rauchgas reduziert werden. Man unterscheidet dabei Primärmaßnahmen, die die Bildung von Schadstoffen verringern sollen, und Sekundärmaßnahmen, die die Abscheidung von Schadstoffen aus dem bei der Verbrennung des Mülls entstehenden Rauchgasen betreffen. Zu den Sekundärmaßnahmen zählen im wesentlichen die Entschwefelung, Entstaubung und Entstickung, ggf. auch das Auswaschen von Halogenverbindungen und Schwermetallen. Dazu verwendet man Rauchgas- Reinigungsanlagen, die den Verbrennungseinrichtungen, seien es nun Müllverbrennungsanlagen oder Kraftwerksfeuerungen, nachgeschaltet sind.In general, when it comes to the incineration of waste (household or special waste) it is of great importance that the pollutant levels in the flue gas are reduced. A distinction is made here between primary measures, which are intended to reduce the formation of pollutants, and secondary measures, which relate to the separation of pollutants from the flue gases generated during the combustion of the waste. Secondary measures essentially include desulphurization, dedusting and denitrification, and possibly also the washing out of halogen compounds and heavy metals. Flue gas cleaning systems are used for this purpose, which are connected downstream of the incineration facilities, be they waste incineration plants or power plant combustion systems.
Zur Einhaltung der immer strengeren Grenzwertvorschriften und zur Senkung der Aufwendungen für die Sekundärmaßnahmen, werden die Primärmäßnahmen, d.h. Maßnahmen zur Vermeidung der Schadstoffbildung, immer wichtiger. Diese bestehen z.B. in der Vermeidung der Staubbildung in der Verbrennungsführung und in der Verringerung schwefelhaltiger Schadstoffe bei der Auswahl der Brennstoffe.In order to comply with the ever stricter limit values and to reduce the expenses for secondary measures, the primary measures, i.e. Measures to avoid pollutant formation, more and more important. These consist e.g. in avoiding dust formation in the combustion process and in reducing sulfur-containing pollutants when selecting the fuels.
Erhebliche Anstrengungen werden zur Reduzierung der Nox- Emissionen unternommen. Man kennt sieben verschiedene Stickoxide, von denen Stickstoffmonoxid (NO) und Stickstoffdioxid (No2) am stabilsten sind und daher im wesentlichen die Stickoxid-Belastung des Rauchgases ausmachen. Dabei entsteht Stickstoffmonoxid in der Hauptsache bei hinreichend langen Verweilzeiten der Verbrennungsgase im Brennraum bei hohen Temperaturen und genügend Luft ohne eine chemische Reaktionen mit dem Brennstoff. Da die Verbrennungsluft zu 78 % aus Stickstoff und 21 % aus Sauerstoff besteht, mächen unter Umständen die aus dem Luftstickstoff gebildeten Stickoxide den größten Teil der Schadstoffbelastung aus. Je nach Brennstoff und Feuerungsart entstehen zwischen 500 und 2000 mg Stickoxide pro m3 Rauchgas. Dabei rechnet man bei Müllverbrennungsanlagen mit einer Kapazität von 100.000 Tonnen Müll pro Jahr mit etwa 860 Mio. Norm- Kubikmeter (Nm3) Rauchgas, bei Sondermüll- Verbrennungsanlagen mit einer Kapazität von 50.000 Tonnen pro Jahr mit etwa 430 Mio. Nm3 Rauchgas.Significant efforts are being made to reduce No x emissions. Seven different nitrogen oxides are known, of which nitrogen monoxide (NO) and nitrogen dioxide (No 2 ) are the most stable and therefore essentially constitute the nitrogen oxide pollution of the flue gas. The main reason for this is that nitrogen monoxide is formed when the combustion gases remain in the combustion chamber for a sufficiently long time at high temperatures and with enough air without chemical reactions with the fuel. Since the combustion air consists of 78% nitrogen and 21% oxygen, the nitrogen oxides formed from the atmospheric nitrogen may make up the largest part of the pollution. Depending on the fuel and type of firing, between 500 and 2000 mg nitrogen oxides per m 3 of flue gas. For waste incineration plants with a capacity of 100,000 tons of waste per year with around 860 million standard cubic meters (Nm 3 ) of flue gas, with special waste incineration plants with a capacity of 50,000 tons per year with around 430 million Nm 3 of flue gas.
Die weitere Entwicklung der Primärmaßnahmen ist auch deshalb wichtig, weil die Entstickung von Rauchgasen durch katalytische Reduktion mit Ammoniakgas zu einem bei hohen Temperaturen (200 bis 250°C) und zum anderen nach der Entschwefelung und Entstaubung durchgeführt wird, um den Katalysator zu schonen. Dazu muß das in der Entschwefelungsanlage abgekühlte Rauchgas unter hohem Energiebedarf wieder aufgeheizt werden.The further development of the primary measures is also important because the denitrification of flue gases by catalytic reduction with ammonia gas is carried out at high temperatures (200 to 250 ° C) and after desulfurization and dedusting to protect the catalyst. For this purpose, the flue gas cooled in the desulfurization system has to be heated up again with a high energy requirement.
Eine andere Möglichkeit zur Verhinderung der Stickoxidbildung ist die sogenannte pulsierende Verbrennung bei Luftüberschuß. Dabei wir durch Schwingungsgeneratoren die Verbrennungsluft stoßweise (pulsierend) aufgegeben, so daß der Brennstoff und die Verbrennungluft optimal gemischt werden. Aus thermodynamisehen und kinetischen Gründen wird so die Stickoxidbildung weitestgehend reduziert, allerdings unter der Voraussetzung, daß mit geeigneten Frequenzen und Amplituden gearbeitet wird (vgl. N. Awerbuch, "Verhinderung der NOx-Bildung durch pulsierende Verbrennungsluft", Verfahrenstechnik 26 (1992) Nr. 12 und 27 (1993) Nr. 3). Diese Verfahren sind jedoch sehr aufwendig und nicht für alle Materialien geeignet.Another possibility for preventing nitrogen oxide formation is the so-called pulsating combustion with excess air. We use vibration generators to give up the combustion air intermittently (pulsating) so that the fuel and the combustion air are optimally mixed. For thermodynamic and kinetic reasons, nitrogen oxide formation is reduced as far as possible, however, provided that suitable frequencies and amplitudes are used (cf. N. Awerbuch, "Prevention of NO x formation by pulsating combustion air", Process Engineering 26 (1992) No. 12 and 27 (1993) No. 3). However, these processes are very complex and are not suitable for all materials.
Aufgabe der Erfindung ist es daher, ein Verfahren und eine Vorrichtung zur Reduzierung der Emissionen bei der Verbrennung von Abfällen. zu schaffen, bei dem die Emissionen in der in die Atmosphäre gelangenden Abluft weiterhin vermindert sind. Dabei sollen insbesondere herkömmliche Drehrohranlagen einsetzbar sein, d.h. es sollen durch die Verwendung reinen Sauerstoffs keine Temperaturen entstehen, die mit der vorhandenen Auslegung dieser Anlagen inkompatibel sind. Andererseits soll die Bildung von Emissionen, insbesondere von Stickoxiden, drastisch reduziert werden. Dies soll auch so erreicht werden, daß man vorhandene Altanlagen umrüsten kann.The object of the invention is therefore a method and a device for reducing the emissions from the incineration of waste. to create, in which the emissions in the exhaust air entering the atmosphere are further reduced. In particular, conventional rotary tube systems can be used, ie the use of pure oxygen should not result in temperatures that are incompatible with the existing design of these systems. On the other hand, the formation of emissions, especially nitrogen oxides, should be drastically reduced. This should also be achieved in such a way that existing systems can be converted.
Die Lösung dieser Aufgabe besteht erfindungsgemäß darin, daß die Rückführung des Rauchgases an den Eingang der Verbrennungsanlage als kontinuierlicher Kreislauf erfolgt, daß die Rauchgas-Reinigungsanlage zweistufig ausgebildet ist und die Rückführung des Rauchgases nach einer Reinigung in der ersten Stufe der Rauchgas- Reinigungsanlage erfolgt und daß das Verhältnis von Rauchgas und Sauerstoff in der am vorderen Teil der Verbrennungsanlage zugegebenen durch Mischung von Rauchgas und reinem Sauerstoff gebildeten synthetischen Luft 4:1 bis 1:1, vorzugsweise im Verhältnis 1,5:1 bis 2:1 ist.The solution to this problem is, according to the invention, that the return of the flue gas to the entrance of the incinerator takes place as a continuous cycle, that the flue gas cleaning system is designed in two stages and that the flue gas is returned after cleaning in the first stage of the flue gas cleaning system and that the ratio of flue gas and oxygen in the synthetic air added at the front of the incinerator, which is formed by mixing flue gas and pure oxygen, is 4: 1 to 1: 1, preferably in the ratio 1.5: 1 to 2: 1.
Durch das erfindungsgemäße Verfahren wird derjenige Anteil der Stickoxide im Rauchgas, welcher bei herkömmlichen Anlagen, die mit Luft arbeiten, der thermischen NO^-Bildung zuzuschreiben ist, drastisch reduziert und ggf. bis auf Null gesenkt. Damit kann der Gesamtstickoxidgehalt des Rauchgases im Extremfall sogar soweit gesenkt werden, daß keine Entstickungsanlage mehr notwendig ist, weil die gesetzlich vorgeschriebenen Grenzwerte von vorne herein unterschritten werden.The process according to the invention drastically reduces the proportion of nitrogen oxides in the flue gas which is attributable to the thermal NO ^ formation in conventional systems which work with air, and possibly reduced to zero. In extreme cases, the total nitrogen oxide content of the flue gas can thus be reduced to such an extent that a denitrification system is no longer necessary because the legally prescribed limit values are undershot from the outset.
Die Mischung von Rauchgas (C02) mit reinem Sauerstoff ergibt eine "synthetische Luft", in der kein Stickstoff mehr enthalten ist, so daß auch durch die Verbrennung selbst keine Stickoxide mehr entstehen können, insbesondere wenn man gemäß einer vorteilhaften Weiterbildung der Erfindung (Anspruch 13) an den Enden eines Drehrohrs, das die Verbrennungsanlage bildet, Schutzeinrichtungen vorsieht, denen Rauchgas als Schutzgas gegen das Einziehen von Falschluft zugeführt wird.The mixture of flue gas (C0 2 ) with pure oxygen results in a "synthetic air", in which nitrogen is no longer contained, so that nitrogen oxides can no longer be produced by the combustion itself, especially if one uses an advantageous method Further development of the invention (claim 13) at the ends of a rotary tube, which forms the incinerator, provides protective devices to which flue gas is supplied as a protective gas against the drawing in of false air.
Das erfindungsgemäße Verfahren und eine danach arbeitende Vorrichtung senken aber nicht nur den Ausstoß der Stickoxide, sondern insgesamt den Ausstoß aller Emissionen, da ein hoher Anteil des Rauchgases und mit ihm somit ein entsprechend hoher Anteil der bei der Verbrennung entstehenden Schadstoffe ja nicht in die Atmosphäre, sondern in die Rauchgasrückführung gelangt und somit im Rauchgaskreisiauf bleibt. Ein besonderes Merkmal des Verfahrens ist es daher, daß insgesamt - bezogen auf ein bestimmtes Volumen an zu verbrennendem Abfall - nur ein Teil des Abgases, nämlich soweit es nicht im Kreislauf rückgeführt wird, in die Atmosphäre gelangt. Es erreicht also nur diejenige Rauchgasmenge den Kamin, die bei der Oxidation des Sonderabfalls durch den im Verbrennungsgas enthaltenen Sauerstoff entsteht. Die übrige Rauchgasmenge läuft kontinuierlich im Kreislauf um. Das hat den zusätzlichen Vorteil, daß insgesamt alle Schadstoffe um bis zu 80% reduziert werden. So werden also gleichzeitig die Stickoxidmengen drastisch gesenkt und das Rauchgasvolumen, das die Anlage verläßt, um bis zu 80% vermindert.However, the method according to the invention and a device operating according to it not only reduce the emission of nitrogen oxides, but overall the emission of all emissions, since a high proportion of the flue gas and thus a correspondingly high proportion of the pollutants produced during combustion do not enter the atmosphere, but gets into the flue gas recirculation and thus remains in the flue gas circuit. It is therefore a special feature of the method that, overall - based on a certain volume of waste to be incinerated - only part of the exhaust gas, namely as far as it is not recycled, is released into the atmosphere. So only the amount of flue gas reaches the chimney that arises from the oxidation of the hazardous waste by the oxygen contained in the combustion gas. The remaining amount of flue gas circulates continuously. This has the additional advantage that all pollutants are reduced by up to 80%. So at the same time the nitrogen oxide quantities are drastically reduced and the flue gas volume that leaves the system is reduced by up to 80%.
Dies soll durch folgendes Zahlenbeispiel verdeutlicht werden: An einer Sonderabfallverbrennunganlage, die mit einer Abgasrückführung gemäß der Erfindung ausgerüstet ist, liegt die DampfProduktion bei ca. 24 t/h, wenn man ca. 4 t/h Abfall mit einem itterlen Heizwert von 15 MJ/kg verbrennt. Der Dampf entsteht bei einem Druck von ca. 32 bar und bei einer Temperatur von ca. 350°C. Obwohl aus Gründen der Wärmeübertragung ca. 20.000-40.000 Nm3/h C02-haltiges Kreislaufgas zirkulieren, geht als Überschußgas eine Menge von nicht mehr als 6000-7000 Nm3/h über den Kamin in die Umgebung. Aufgrund der hohen volummetrischen Wärmekapazität des C02-reichen Verbrennungsgases können die Wärmestromdichten je nach Drehrohrauslegung von 150 KW/m3 auf 200-300 KW/m3 gesteigert werden.This is to be illustrated by the following numerical example: In a special waste incineration plant which is equipped with an exhaust gas recirculation according to the invention, the steam production is approx. 24 t / h, if approx. 4 t / h waste with an average calorific value of 15 MJ / kg burns. The steam is generated at a pressure of approx. 32 bar and at a temperature of approx. 350 ° C. Although for reasons of heat transfer approx. 20,000-40,000 Nm 3 / h Circulating C0 2 -containing circulating gas, the excess gas is a quantity of not more than 6000-7000 Nm 3 / h through the chimney into the environment. Due to the high volumetric heat capacity of the C0 2 -rich combustion gas, the heat flow densities can be increased from 150 KW / m 3 to 200-300 KW / m 3 depending on the design of the rotary tube.
Damit nun im Rauchgaskreisiauf keine Aufkonzentration oder Anreicherung der Emissionen erfolgt, besteht ein weiteres Merkmal der Erfindung darin, innerhalb des Kreislaufs die erste Stufe der Rauchgas-Reinigungsanlage vorzusehen, die insbesondere so eingerichtet ist (vgl. Anspruch 9), daß dem Rauchgas Staub, Chlor, Schwermetalle und Schwefeldioxid entzogen werden. Die zweite Stufe der Rauchgas-Reinigungsanlage, durch die der Anteil Rauchgas hindurchgeht, der nicht im Kreislauf zurückgeführt wird, dient dann zur Reinigung von Dioxinen, Furanen, ferner zur Restreinigung von Schwefeldioxid, Schwermetallen und - sofern überhaupt noch erforderlich - von Stickoxiden (Anspruch 10). Diese Aufteilung der Rauchgas- Reinigungsanlage in zwei Stufen und die Einbeziehung der ersten Stufe in den kontinuierlichen Rauchgaskreisiauf hat zur Folge, daß eine Anreicherung von Schadstoffen im Kreislauf vermieden wird. Die Anforderungen an diese erste Stufe der Rauchgas-Reinigungsanlage sind insoweit nicht sehr streng, da der in die Atmosphäre abgeleitete "Rest" des die erste Stufe verlassenden Rauchgases in der zweiten Stufe - soweit noch erforderlich - vollends auf die kritischen Grenzwerte herabgereinigt wird.So that there is no concentration or enrichment of the emissions in the flue gas circuit, a further feature of the invention is to provide the first stage of the flue gas cleaning system within the circuit, which is in particular set up (cf. claim 9) that the flue gas is dust, chlorine , Heavy metals and sulfur dioxide are removed. The second stage of the flue gas cleaning system, through which the part of flue gas that does not go back into the circuit passes, then serves to purify dioxins, furans, and also to purify sulfur dioxide, heavy metals and - if necessary at all - nitrogen oxides (claim 10 ). This division of the flue gas cleaning system into two stages and the inclusion of the first stage in the continuous flue gas circuit has the result that an accumulation of pollutants in the circuit is avoided. The requirements for this first stage of the flue gas cleaning system are not very strict in this respect, since the "rest" of the flue gas leaving the first stage, which is discharged into the atmosphere, is completely cleaned down to the critical limit values in the second stage, if necessary.
Dabei ist das Verhältnis von Rauchgas (C0a) zu Sauerstoff mit 4:1 bis 1:1 angegeben. Ein besonders bevorzugter Bereich ist 2:1 bis 1,5:1. Die Mengenverhältnisse werden zur Beeinflussung der Flammentemperatur in Anpassung an die verschiedenen Materialien, die verbrannt werden, sowie zur Optimierung des gesamten Verbrennungsvorganges gesteuert.The ratio of flue gas (C0 a ) to oxygen is 4: 1 to 1: 1. A particularly preferred range is 2: 1 to 1.5: 1. The proportions are used to influence the flame temperature in adaptation to the different materials that are burned as well as to optimize the entire combustion process.
Eine vorteilhafte Weiterbildung der Erfindung sieht vor, daß die Regelung des Verbrennungsvorganges durch Zugabe fluider Stützenergieträger erfolgt (Anspruch 2), insbesondere durch gereinigtes Pyrolysegas und Pyrolyseöl, die in einer vorgeschalteten Pyrolyse erzeugt werden (Anspruch 6). Durch die vorgeschaltete Pyrolyse werden dem Sonderabfall vor der Verbrennung Anteile an heizwertreichen Abfall entzogen. Das Rauchgasvolumen wird dadurch gesenkt. Ein weiterer Vorteil ist, daß gefährliche Giftstoffe wie PCB, Dioxine, Furane, etc. sowie stickstoffhaltige Substanzen zerstört werden. Auf diese Weise wird also die NOx-Bildung noch weiter reduziert.An advantageous development of the invention provides that the combustion process is controlled by adding fluid support energy sources (claim 2), in particular by purified pyrolysis gas and pyrolysis oil, which are produced in an upstream pyrolysis (claim 6). The upstream pyrolysis removes portions of high-calorific waste from the hazardous waste before incineration. This reduces the flue gas volume. Another advantage is that dangerous toxins such as PCB, dioxins, furans, etc. and nitrogenous substances are destroyed. In this way, the NO x formation is reduced even further.
Vorteilhafterweise wird der Sauerstoff in einer Luftzerlegungsanlage mit Hilfe der bei der Verbrennung gewonnenen Prozeßenergie erzeugt (Anspruch 3). Bei der Luftzerlegung erhält man außer Sauerstoff im wesentlichen auch noch Stickstoff, der als Schutzgas bei der der Verbrennung bzw. Pyrolyse vorgeschalteten Zerkleinerung des Sonderabfalls dienen kann (Anspruch 5).The oxygen is advantageously generated in an air separation plant with the aid of the process energy obtained in the combustion (claim 3). In air separation, in addition to oxygen, essentially nitrogen is also obtained, which can serve as a protective gas in the comminution of the special waste prior to combustion or pyrolysis (claim 5).
Wenn man die vorgeschaltete Pyrolyse mit heizwertreichem Abfall (Anspruch 7), insbesondere in Form sondermüllähnlicher Abfälle, wie z.B. Kunststoffabfallen oder Autoreifen beschickt, erzielt man zusätzlich einen Energie-Recycling-Effekt. Beträgt die Menge der zu pyrolysierenden Abfälle mindestens 20 bis 25 % der zu verbrennenden Abfälle (Anspruch 8), reicht das so gewonnene Pyrolysegas und Pyrolyseöl aus, um die gesamte Verbrennung autark zu betreiben. Damit ist man nicht mehr auf fossilen Energieträger (Öl, Gas) zur Bereitstellung der Stützenergie angewiesen. Ein erheblicher Vorteil des erfindungsgemäßen Verfahrens besteht ferner darin, daß die Wärmetransporteigenschaften der erfindungsgemäß gebildeten "synthetischen Luft", bestehend aus Rauchgas (C02) und Sauerstoff, sehr viel besser als die der normalen Luft, bestehend aus Stickstoff und Sauerstoff, sind (Anspruch 11, 12). Legt man z.B. der Verbrennungsluft im Normalfall eine Zusammensetzung von 75 Vol.-Prozent Stickstoff, 13,3 Vol.-Prozent Sauerstoff und 11,7 Vol.-Prozent H20 zugrunde, wobei man ferner von der Dichte der Komponenten bei 1000°C ausgeht, so ergibt sich eine volumenspezifische Wärmekapazität von 0,36 kJ/m3.k. Legt man bei der "synthetischen Luft" gemäß der Erfindung 75 Vol.-Prozent C02, 13,3 Vol.-Prozent 02 und 11,7 Vol.- Prozent H20 zugrunde, so ergibt sich daraus eine volumenspezifische Wärmekapazität von 0,53 kJ/m3.k. Bei gleichem Volumendurchsätzen ist also der Wärmetransport bei sonst gleichen Bedingungen bei der synthetischen Luft um 47 % besser als bei normaler Luft. Die Prandtl-Zahl liegt bei Luft und synthetischer Luft unter 1, d.h. die räumliche Ausdehnung der thermischen Grenzschicht ist größer als die der aerodynamischen Grenzschicht, was auf einen vergleichbaren Wärmeübergang bei beiden Gasgemischen, bspw. auf Kesselwärme-Übertragungsflächen, schließen läßt. Der dargestellte Unterschied in der Wärmekapazität und die erhöhte Wärmekapazität der synthetische Luft hat die Konsequenz, daß die Verbrennungsleistung bei ansonsten gleicher Auslegung einer Anlage auf das 1,5-fache steigerbar ist. Man kann also, wenn man bestehende Anlagen gemäß der Erfindung umrüstet, gleichzeitig die Leistungsfreisetzung steigern. Dies ist ein weiterer ganz bedeutender Vorteil der Erfindung. Sollte sich herausstellen, daß dabei der Wärmeübergang durch die "normale" Dimensionierung der Wärmeübergangsfläche am Kessel zu gering ist, so kann man die Wärmeübertragungsfläche leicht vergrößern. Aus dieser Steigerung des Wärmedurchsatzes verändert sich gegenüber der herkömmlichen Fahrweise auch die Strömungsgeschwindigkeit. Durch Regelung der Strömungsgeschwindigkeit wird eine stabile Flamme am Brenner und somit ein stabiler Verbrennungsprozeß gewährleistet. Zu diesem Zweck sieht eine vorteilhafte Weiterbildung der Erfindung vor (Anspruch 12), daß in der Leitung zur Rückführung des gereinigten Rauchgases Regelungseinrichtungen angeordnet sind.If you feed the upstream pyrolysis with high-calorific waste (claim 7), in particular in the form of hazardous waste, such as plastic waste or car tires, an additional energy recycling effect is achieved. If the amount of waste to be pyrolyzed is at least 20 to 25% of the waste to be incinerated (claim 8), the pyrolysis gas and pyrolysis oil thus obtained are sufficient to operate the entire incineration independently. This means that you are no longer dependent on fossil fuels (oil, gas) to provide the support energy. A significant advantage of the method according to the invention is also that the heat transport properties of the "synthetic air" formed according to the invention, consisting of flue gas (CO 2 ) and oxygen, are much better than that of normal air, consisting of nitrogen and oxygen , 12). If, for example, the combustion air is normally based on a composition of 75% by volume nitrogen, 13.3% by volume oxygen and 11.7% by volume H 2 0, the density of the components at 1000 ° C. also being used assumes a volume-specific heat capacity of 0.36 kJ / m 3 .k. If one bases the “synthetic air” according to the invention on 75 volume percent CO 2 , 13.3 volume percent 0 2 and 11.7 volume percent H 2 0, this results in a volume-specific heat capacity of 0 , 53 kJ / m 3 .k. With the same volume throughputs, the heat transport in otherwise identical conditions is 47% better for synthetic air than for normal air. The Prandtl number for air and synthetic air is less than 1, ie the spatial extent of the thermal boundary layer is greater than that of the aerodynamic boundary layer, which suggests a comparable heat transfer for both gas mixtures, e.g. boiler heat transfer surfaces. The difference shown in the heat capacity and the increased heat capacity of the synthetic air has the consequence that the combustion output can be increased 1.5 times with the otherwise identical design of a system. So if you retrofit existing systems according to the invention, you can increase the power release at the same time. This is another very important advantage of the invention. If it turns out that the heat transfer due to the "normal" dimensioning of the heat transfer surface on the boiler is too small, the heat transfer surface can be easily increased. This increase in heat throughput also changes the flow rate compared to conventional driving. By regulating the flow rate, a stable flame on the burner and thus a stable combustion process is ensured. For this purpose, an advantageous development of the invention provides that control devices are arranged in the line for returning the cleaned flue gas.
Auch bei vollständiger Speisung des Drehrohrs mit synthetischer Luft aus Rauchgas und Sauerstoff ist es immerhin möglich, daß dennoch in dem Verbrennungsraum, z.B. in ein Drehrohr an seinen Dichtungen, Stickstoff enthaltende Luft als "Falschluft" eingezogen wird. Um auch diese Quelle für die Entstehung von NO,, bei der Verbrennung zu beseitigen, sieht eine vorteilhafte Weiterbildung der Erfindung (Anspruch 15) vor, daß an den Dichtungen Schutzeinrichtungen vorgesehen sind, denen als Schutzgas Rauchgas zugeführt wird.Even if the rotary tube is completely supplied with synthetic air from flue gas and oxygen, it is still possible that in the combustion chamber, e.g. Air containing nitrogen is drawn into a rotary tube at its seals as "false air". In order to eliminate this source for the formation of NO ,, during combustion, an advantageous development of the invention (claim 15) provides that protective devices are provided on the seals, to which flue gas is supplied as protective gas.
Ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens wird im folgenden anhand der beigefügten Zeichnungen beschrieben. Es zeigen:An embodiment of the method according to the invention is described below with reference to the accompanying drawings. Show it:
Figur 1 den Verfahrensablauf;Figure 1 shows the process flow;
Figur 2 ein Detail der in Figur 1 lediglich schematisch angedeuteten Abdichtungseinrichtung 45 am vorderen Ende la des Drehrohres 1.FIG. 2 shows a detail of the sealing device 45 at the front end 1 a of the rotary tube 1, which is indicated only schematically in FIG. 1.
Der Sonderabfall wird, nachdem der pyrolysierbare Anteil vorher abgetrennt wurde, in einem Drehrohr 1, das als Verbrennungsraum dient, gebracht. Ein regelbarer Energieträger, d.h. ein fluider Brennstoff, wird über Leitungen 2 zugeführt. Dabei kann es sich um fossile Erdenergieträger, wie Öl oder Gas, handeln. Dabei werden Produkte einer vorgeschalteten Pyrolyse 3 eingesetzt. In der Pyrolyse werden heizwertreiche Abfälle (d.h. mit einem Energiegehalt von mehr als 25 J/kg) aus dem Sonderabfallgemisch, z.B. nicht mehr recycelbare Kunststoffe, Elektronikschrott oder Siebüberläufe oder andere heizwerte sonderabfallähnliche Stoffe wie Abfall- Kunststoffe oder Autoreifen bei 480 bis 700°C pyrolysiert. Das gereinigte Pyrolysegas und/oder das Pyrolyseöl werden in die Leitung 2 eingespeist. Die Menge der pyrolysierbaren Abfälle sollte mindestens 40 bis 50 % der Sonderabfallmenge betragen. So ist die Verbrennung der gesamten Anlage energieautark.The special waste, after the pyrolysable portion has been separated beforehand, is placed in a rotary tube 1, which serves as a combustion chamber. A controllable energy source, ie a fluid fuel, is supplied via lines 2. It can be fossil Earth energy sources, such as oil or gas. Products of an upstream pyrolysis 3 are used. In the pyrolysis, high-calorific waste (i.e. with an energy content of more than 25 J / kg) from the special waste mixture, e.g. no longer recyclable plastics, electronic scrap or screen overflows or other calorific-like special waste-like materials such as waste plastics or car tires are pyrolyzed at 480 to 700 ° C . The cleaned pyrolysis gas and / or the pyrolysis oil are fed into line 2. The amount of pyrolyzable waste should be at least 40 to 50% of the amount of hazardous waste. The combustion of the entire system is energy self-sufficient.
Die Brennstoffleitung 2 verzweigt sich in eine Leitung 2a, die zu einem Brenner 4a am vorderen Ende la des Drehrohres l führt, und eine Leitung 2b, die zu einem Brenner 4b in einer Nachbrennkammer 5 führt. Das DrehrohrThe fuel line 2 branches into a line 2a, which leads to a burner 4a at the front end la of the rotary tube 1, and a line 2b, which leads to a burner 4b in an afterburning chamber 5. The rotary tube
1 wird über eine Leitung 6, die in das vordere Ende la des Drehrohres 1 mündet, der Brenner 4a über die Leitung 7 mit synthetischer Luft versorgt. Die synthetische Luft wird in einer Mischkammer 21 erzeugt, der einerseits über die Leitung 20 Rauchgas, also im wesentlichen C02, und andererseits Sauerstoff zugeführt wird, der in einer Luftzerlegungsanlage 23 hergestellt wird. Diese synthetische Luft wird dem in Strömungsrichtung vorderen Ende la in Nähe des Brenners 4a dem hinteren Ende lb des Drehrohres l zugeführt. Zusammen mit dem über die Leitung1, the burner 4a is supplied via line 7 with synthetic air via a line 6, which opens into the front end 1 a of the rotary tube 1. The synthetic air is generated in a mixing chamber 21 which, on the one hand, is supplied with flue gas, ie essentially C0 2 , via line 20 and, on the other hand, oxygen which is produced in an air separation plant 23. This synthetic air is fed to the front end la in the flow direction in the vicinity of the burner 4a to the rear end lb of the rotary tube l. Along with that over the line
2 zugeführten und aus der Pyrolyse 3 stammenden fluiden Brennstoff, der als Stutzenergieträger dient, erfolgt damit die Verbrennung der Abfälle, die dem Drehrohr 1 über eine Hochdruckleitung 60 durch Verpumpen quasi kontinuierlich zugefügt wird.2 supplied and from the pyrolysis 3 fluid fuel, which serves as a support energy source, the waste is thus incinerated, which is quasi continuously added to the rotary tube 1 via a high-pressure line 60 by pumping.
Der Sonderabfall wird im Drehrohr 1 verbrannt und wandert dabei von einem Bereich niedriger Temperatur von ca. 400 bis 700°C am vorderen Ende la bis zu einem Bereich höherer Temperatur von ca. 1200 bis 1300°C am hinteren Ende lb. Anschließend gelangt das bei der Verbrennung entstehende Rauchgas in die bereits erwähnte Nachbrennkammer 5, in der der Brenner 4b angeordnet ist, dem die synthetische Luft über die Leitung 8 und ein fluider Brennstoff über die Leitung 2b zugeführt wird. In der Nachbrennkammer 5 erfolgt eine Nachverbrennung. Die ausgebrannte schmelzflüssige Schlacke wird am Ausgang 10 abgezogen und in einem Wasserbad abgeschreckt.The hazardous waste is burned in the rotary tube 1 and moves from a low temperature area of approx. 400 up to 700 ° C at the front end la up to a higher temperature range of approx. 1200 to 1300 ° C at the rear end lb. Subsequently, the flue gas generated during the combustion passes into the afterburning chamber 5 already mentioned, in which the burner 4b is arranged, to which the synthetic air is fed via line 8 and a fluid fuel via line 2b. Afterburning takes place in the afterburning chamber 5. The burned-out molten slag is drawn off at exit 10 and quenched in a water bath.
Das Rauchgas gelangt von der Nachbrennkammer 5 in einen Strahlungsteil 11, wo es abgekühlt wird und von dort in einen Abhitzekessel 12 mit einem Konvektionswärmetauscher 13. Das Rauchgas dient dabei unter weiterer Abkühlung zur Erzeugung von Dampf, der zur Stromerzeugung verwendet wird (hier nicht dargestellt).The flue gas passes from the afterburning chamber 5 into a radiation part 11, where it is cooled and from there into a waste heat boiler 12 with a convection heat exchanger 13. The flue gas is used with further cooling to generate steam which is used to generate electricity (not shown here) .
Anschließend gelangt das abgekühlte Rauchgas, das noch eine Temperatur von etwa 300 bis 400°C aufweist, in eine zweistufige Rauchgas-Reinigungsanlage, deren erste Stufe mit 14 und deren zweite Stufe mit 24 bezeichnet ist. In der ersten Stufe 14 der Rauchgas-Reinigungsanlage erfolgt die Abscheidung von Staub, Chlorverbindungen (insbesondere HC1), Schwefeldioxid und Schwermetallen. Dabei kann die erste Stufe 14 als Folge einzelner Abschnitte, die den einzelnen Reinigungsaufgaben zugeordnet sind, ausgebildet sein. Dem Fachmann ist dies bekannt. Daher ist es im folgenden Zusammenhang im einzelnen nicht näher ausgeführt.The cooled flue gas, which still has a temperature of approximately 300 to 400 ° C., then passes into a two-stage flue gas cleaning system, the first stage of which is designated by 14 and the second stage is designated by 24. In the first stage 14 of the flue gas cleaning system, dust, chlorine compounds (especially HC1), sulfur dioxide and heavy metals are separated. The first stage 14 can be designed as a sequence of individual sections which are assigned to the individual cleaning tasks. This is known to the person skilled in the art. It is therefore not explained in detail in the following context.
Das in der ersten Stufe 14 der Rauchgas-Reinigungsanlage gereinigte Rauchgas wird zu einem Teil, der mit der Regelklappe 61 eingestellt wird, über die Leitung 20 zurückgeführt, wobei, wie bereits erwähnt, in der Mischkammer 21 reiner Sauerstoff zugemischt wird, um die zur Verbrennung im Drehrohr 1 erforderliche synthetische Luft zu erhalten.The flue gas cleaned in the first stage 14 of the flue gas cleaning system is returned to a part that is set with the control flap 61 via the line 20, wherein, as already mentioned, pure oxygen is mixed in to the mixing chamber 21 in order to to obtain synthetic air required for combustion in the rotary tube 1.
Dabei ist zunächst im Prinzip davon auszugehen, daß der Anteil rückgeführten Rauchgases dem Anteil des Stickstoffs in der normalen Luft (4:1) entspricht. Er kann jedoch geringer gewählt werden, um eine Luftzahl lambda größer 1 zu erzeugen, um dadurch optimale Betriebsbedingungen einzustellen. Die Einstellung wird, wie bereits eingangs ausgeführt, so erfolgen, daß das Verhältnis von Rauchgas zu Sauerstoff hinter der Mischkammer 21 in den Leitungen 6, 7, 8 zwischen 4:1 und 1:1 schwankt. Bevorzugt liegt es im Bereich 2:1 bis 1,5:1.In principle, it must be assumed that the proportion of returned flue gas corresponds to the proportion of nitrogen in normal air (4: 1). However, it can be selected lower in order to generate an air ratio lambda greater than 1 in order to thereby set optimal operating conditions. As already stated at the beginning, the setting is carried out such that the ratio of flue gas to oxygen behind the mixing chamber 21 in the lines 6, 7, 8 fluctuates between 4: 1 and 1: 1. It is preferably in the range 2: 1 to 1.5: 1.
Dieser Rauchgaskreisiauf hat zur Folge, daß das Drehrohr nicht, wie es eine Verbrennung mit reinem Sauerstoff zur Folge hätte, Temperaturen erreicht, die für herkömmliche Verbrennungstechnologien zu hoch sind. Andererseits verbleibt ein Großteil des bei der Verbrennung entstehenden Rauchgases im kontinuierlichen Rauchgaskreisiauf. Von Bedeutung ist, daß innerhalb des Kreislaufes in der ersten Stufe 14 der Rauchgas- Reinigungsanlage ein ständiges Auswaschen der schädlichen Emissionsanteile im Rauchgas erfolgt. Die Reinigung in der ersten Stufe 14 ist so ausgelegt, daß sich im Kreislauf keine Anreicherung dieser Anteile ergibt, die - z.B. bei HC1 - zur Korrosion der Verbrennungsanlage oder zur Erhöhung der Emission von Schadstoffen in dem Anteil des Rauchgases, der ins Freie gelangt, führen könnten. Diese ständige Reinigung des Rauchgases im Kreislauf hat zur Folge, daß der Anteil von schädlichen Abgasen in dem Teil des Rauchgases, der über die Leitung 19 und dann nach der zweiten Stufe 24 der Rauchgas-Reinigungsanlage schließlich über den Kamin 27 ins Freie gelangt, gegenüber herkömmlichen Anlagen schon deshalb erheblich reduziert ist, weil insgesamt der Teil des in die Atmosphäre abgegebenen Rauchgases sehr viel geringer als bei herkömmlichen Anlagen ist. Die Rauchgasmenge kann von etwa 7,5 x 103 m3 pro Tonne bei bekannten Verfahren auf etwa 1,5 x 103 m3 pro Tonne Sonderabfall reduziert werden.The result of this flue gas circuit is that the rotary tube does not, as would result in combustion with pure oxygen, reach temperatures which are too high for conventional combustion technologies. On the other hand, a large part of the flue gas generated during combustion remains in the continuous flue gas circuit. It is important that within the circuit in the first stage 14 of the flue gas cleaning system there is a constant washing out of the harmful emissions in the flue gas. The cleaning in the first stage 14 is designed in such a way that there is no accumulation of these components in the circuit, which - for example in the case of HC1 - lead to corrosion of the incinerator or to an increase in the emission of pollutants in the portion of the flue gas that is released into the open could. This constant cleaning of the flue gas in the circuit has the result that the proportion of harmful exhaust gases in the part of the flue gas that finally comes out via the line 19 and then after the second stage 24 of the flue gas cleaning system via the chimney 27, compared to conventional ones Systems are therefore considerable is reduced because overall the part of the flue gas released into the atmosphere is much lower than in conventional systems. The amount of flue gas can be reduced from about 7.5 x 10 3 m 3 per ton in known processes to about 1.5 x 10 3 m 3 per ton of special waste.
Insbesondere erfolgt eine Verringerung der Stickoxide bei dieser Form der Verbrennung des Abfalls im Drehrohr 1 mit synthetischer Luft dadurch, daß ja die synthetische Luft kaum Stickstoff mehr enthält, so daß im Drehrohr 1 auch nicht mehr durch Verbrennung des Luftstickstoffes Stickoxide gebildet werden können.In particular, there is a reduction in the nitrogen oxides in this form of combustion of the waste in the rotary tube 1 with synthetic air in that the synthetic air hardly contains any more nitrogen, so that nitrogen oxides can no longer be formed in the rotary tube 1 by combustion of the atmospheric nitrogen.
Über die Leitung 19 gelangt der Teil des Rauchgases, der nicht in der Leitung 20 in den kontinuierlichen Rauchgaskreisiauf zurückgeführt wird, an die zweite Stufe 24, in der die Restreinigung des Rauchgases erfolgt, so insbesondere bezüglich Rest-Schwefeldioxid und Rest- Schwermetallen. Außerdem ist dort die Reinigung von Dioxinen und Furanen in entsprechendenThe part of the flue gas that is not returned to the continuous flue gas circuit in line 20 passes via line 19 to the second stage 24, in which the residual purification of the flue gas takes place, in particular with regard to residual sulfur dioxide and residual heavy metals. There is also the cleaning of dioxins and furans in corresponding
Abscheideeinrichtungen vorgesehen. Evtl. kann, falls je erforderlich, dort auch eine Restreinigung von . Stickoxiden erfolgen, falls diese dennoch gebildet werden, weil durch Undichtigkeiten im gesamten System natürliche Luft eingezogen wird oder weil in dem zur Verbrennung gelangenden Abfall Stickstoffverbindungen enthalten waren.Separation devices are provided. Possibly. can, if necessary, also a residual cleaning of. Nitrogen oxides occur if they are nevertheless formed because natural air is drawn in through leaks in the entire system or because nitrogen compounds were contained in the waste that is incinerated.
Wie bereits eingangs dargelegt, ist die Verbrennungsleistung eines solchen Systems infolge der höheren Wärmekapazität der synthetischen Luft im Vergleich zu herkömmlichen Anlagen um ca. das 1,5-fache erhöht. Diese Steigerung der Verbrennungsleistung führt auch - im Verhältnis von.den Abmessungen her konventionell ausgelegten Verbrennungsanlagen - zu einer veränderten Strömungsgeschwindigkeit, die u.U. zu Abrissen der Flamme des Brenners 4a dienen kann. Dem kann dadurch begegnet werden, daß die Strömungsgeschwindigkeit in den Leitungen 6, 7, 8 geregelt wird. Zu diesem Zweck sind dort Regelungseinrichtungen 40, 41, 42 vorgesehen.As already mentioned at the beginning, the combustion capacity of such a system is increased by approximately 1.5 times as a result of the higher thermal capacity of the synthetic air compared to conventional systems. This increase in combustion performance also leads - in relation to the dimensions of conventionally designed combustion plants - to a changed flow rate, which may Tearing down the flame of the burner 4a can serve. This can be countered by regulating the flow rate in the lines 6, 7, 8. Control devices 40, 41, 42 are provided there for this purpose.
Um zu vermeiden, daß an den Dichtungsstellen des Drehrohrs 1 Falschluft eingezogen wird, deren Stickstoffanteile zu Stickoxiden im Rauchgas führen könnte, sind die Dichtungen des Drehrohres 1 mit Kammern 45 am vorderen Ende la und 46 am rückwärtigen Ende lb versehen, denen über die Leitungen 51, 52 ebenfalls Rauchgas zugeführt wird. Dieses Rauchgas dient bei den Dichtungen als Schutzgas und verhindert das Einziehen von normaler Stickstoff enthaltenden Luft.In order to avoid that false air is drawn in at the sealing points of the rotary tube 1, the nitrogen components of which could lead to nitrogen oxides in the flue gas, the seals of the rotary tube 1 are provided with chambers 45 at the front end 1 a and 46 at the rear end 1 b, which are connected via the lines 51 , 52 flue gas is also supplied. This flue gas serves as a protective gas for the seals and prevents the intake of normal nitrogen-containing air.
Der reine Sauerstoff, der der Mischkammer 21 über die Leitung 22 zugeführt wird, wird in einer Luftzerlegungsanlage 23 gewonnen. Der in der Luftzerlegungsanlage 23 anfallende Stickstoff kann wieder als Schutzgas dienen, und zwar sowohl einerseits - dies wäre eine Modifikation des in der Zeichnung dargestellten Ausführungsbeispiels - bezüglich der Dichtung des Drehrohrsystems, aber auch in der (nicht gezeigten) Zerkleinerungsanlage, in der der Sondermüll vorkonditioniert und für die Verbrennung vorbereitet wird. Das Schutzgas dient dabei zur Unterdrückung der Bildung explosiver Gemische.The pure oxygen, which is fed to the mixing chamber 21 via the line 22, is obtained in an air separation plant 23. The nitrogen produced in the air separation plant 23 can again serve as protective gas, both on the one hand - this would be a modification of the exemplary embodiment shown in the drawing - with regard to the seal of the rotary tube system, but also in the shredding plant (not shown) in which the hazardous waste is preconditioned and being prepared for combustion. The protective gas is used to suppress the formation of explosive mixtures.
Eine detaillierte Ausbildung der Abdichtungseinrichtung 45 am vorderen Ende la des Drehrohrs 1 zeigt Figur 2. Das Drehrohr 1 ist mit zwei Flanschen 62 und 63 versehen, an die Ringe 64 und 65 angeschraubt sind. Die Verschraubung ist durch die strichpunktierten Linien angedeutet. Die Ringe 64, 65 sind aus Montagegründen unterteilt. An dieser Stelle wird das Drehrohr 1 von einem stationären Ringabschnitt 66 umgeben, in dem die Leitung 67, über die Rauchgas zugeführt wird, mündet. Die Leitung 67 in Figur 2 hat dieselbe Funktion wie die Leitung 51 in Figur 1. An dem Ringabschnitt 66 sind zwei im Querschnitt U-förmige Dichtungstragringe 68, 69 angebracht, die jeweils im Querschnitt rechteckige Ausnehmungen 70, 71 aufweisen, die die Ringe 64, 65 umgeben. In den Seitenflächen der Ausnehmungen 70, 71 sind Dichtungsringe 72, 73, sowie 74, 75 aufgenommen. Sie werden von Gruppen von Federn 76, 77, 78, 79 gegen sich mit dem Drehrohr 1 mitdrehenden Ringe 64, 65 gedrückt und bilden so eine Gleitringdichtung. An die Dichtungstragringe 68, 69 sind weitere Flansche 80, 81 angeschweißt. Bei den Dichtungen handelt es sich um bekannte sog. "Burgmann-Dichtungen".FIG. 2 shows a detailed design of the sealing device 45 at the front end 1 a of the rotary tube 1. The rotary tube 1 is provided with two flanges 62 and 63, to which rings 64 and 65 are screwed. The screw connection is indicated by the dash-dotted lines. The rings 64, 65 are divided for reasons of assembly. At this point, the rotary tube 1 is surrounded by a stationary ring section 66, in which the line 67, via the Flue gas is supplied, flows. The line 67 in FIG. 2 has the same function as the line 51 in FIG. 1. On the ring section 66 there are two sealing support rings 68, 69 which are U-shaped in cross section and each have rectangular recesses 70, 71 in cross section, which the rings 64, 65 surrounded. Sealing rings 72, 73 and 74, 75 are accommodated in the side surfaces of the recesses 70, 71. They are pressed by groups of springs 76, 77, 78, 79 against rings 64, 65 which rotate with the rotary tube 1 and thus form a mechanical seal. Further flanges 80, 81 are welded to the seal support rings 68, 69. The seals are known as "Burgmann seals".
Nach links schließt sich in Figur 2 an die beiden Burgmann-Dichtungen ein Kompensator 82 an. Der Kompensator 82 ist an den Kasten 83, der die Stirnwand des Drehrohrofens bildet, angeschweißt. Der Kompensator besteht aus zwei Ringabschnitten 84, 85, zwei senkrecht zur Achse des Drehrohrs stehenden Ringen 86, 87 und einem U-förmigen Kompensationsteil 88. Der Ringabschnitt 85 ist innen mit dem Dichtungstragring 68 verschweißt. Der Kompensator 82 dient zum Ausgleich von Längenveränderungen in Folge der Erhitzung.A compensator 82 adjoins the two Burgmann seals to the left in FIG. The compensator 82 is welded to the box 83, which forms the end wall of the rotary kiln. The compensator consists of two ring sections 84, 85, two rings 86, 87 perpendicular to the axis of the rotary tube and a U-shaped compensation part 88. The ring section 85 is welded to the seal support ring 68 on the inside. The compensator 82 is used to compensate for changes in length due to the heating.
In dem vorderen (in Figur 2: linken) Ende des Drehrohrs herrscht ein Druck von ca. minus 4 - 5 mbar. Da der Druck außerhalb des Drehrohres beispielsweise 1000 mbar ist, besteht also zwischen außen und innen eine erhebliche Druckdifferenz. Ohne besondere Maßnahmen würde sie dazu führen, daß entlang der strichpunktiert eingezeichneten Linie L atmosphärische Luft in das Drehrohr 1 eingezogen wird. Das hätte die Wirkung, daß der in der eingezogenen Falschluft enthaltene Stickstoff im Drehrohr Stickoxide bilden kann. Um dies zu vermeiden, ist vorgesehen, daß über die Leitung 67, wie erwähnt, Rauchgas, und zwar ebenfalls mit einem Druck von 1000 mbar zugeführt wird. Das Rauchgas füllt dann die Räume 89 und 90. Dies hat zur Folge, daß an der Stelle, an der der Dichtungsring 75 auf den Ring 65 drückt, kein Druckgefälle mehr besteht, so daß keine Falschluft entlang der strichpunktiert eingezeichneten Linie L mehr angesaugt wird. Wird andererseits aus den Räumen 89, 90 durch die Dichtung am Ring 64 Rauchgas in das Drehrohr eingesaugt, so kann dies nicht zu einer thermischen Stickoxidbildung führen, da dieses bei der gezeigten Anordnung keinen Stickstoff enthält. Auf diese Weise wird also eine wirksame Schutzgas-Abdichtung erzielt. A pressure of approx. Minus 4 - 5 mbar prevails in the front (in Figure 2: left) end of the rotary tube. Since the pressure outside the rotary tube is, for example, 1000 mbar, there is a considerable pressure difference between the outside and inside. Without special measures, it would lead to atmospheric air being drawn into the rotary tube 1 along the dash-dotted line L. This would have the effect that the nitrogen contained in the drawn-in false air can form nitrogen oxides in the rotary tube. To avoid this, it is provided that, as mentioned, flue gas via line 67, specifically is also supplied at a pressure of 1000 mbar. The flue gas then fills the spaces 89 and 90. This has the consequence that there is no longer a pressure drop at the point at which the sealing ring 75 presses on the ring 65, so that no false air is sucked in anymore along the line L shown in broken lines. If, on the other hand, flue gas is sucked into the rotary tube from the spaces 89, 90 through the seal on the ring 64, this cannot lead to thermal nitrogen oxide formation since this does not contain nitrogen in the arrangement shown. In this way, an effective protective gas seal is achieved.
Claims
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/532,580 US5826521A (en) | 1993-04-22 | 1994-04-09 | Method for reducing the emissions produced by incinerating waste |
| DE9414301U DE9414301U1 (en) | 1993-04-22 | 1994-04-09 | Device for reducing emissions from waste incineration |
| EP94913561A EP0694147B1 (en) | 1993-04-22 | 1994-04-09 | Method of reducing the emissions produced by incinerating waste |
| DE59403467T DE59403467D1 (en) | 1993-04-22 | 1994-04-09 | METHOD FOR REDUCING EMISSIONS FROM COMBUSTION OF WASTE |
| EP95915862A EP0701674B1 (en) | 1994-04-09 | 1995-04-10 | Method of reducing waste-incineration emissions |
| PCT/EP1995/001308 WO1995027872A1 (en) | 1994-04-09 | 1995-04-10 | Method of reducing waste-incineration emissions |
| DE59504964T DE59504964D1 (en) | 1994-04-09 | 1995-04-10 | METHOD FOR REDUCING EMISSION FROM WASTE COMBUSTION |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4313102A DE4313102A1 (en) | 1993-04-22 | 1993-04-22 | Method of reducing the amount of exhaust gas to eliminate NO¶x¶ emissions from combustion, preferably from waste incineration |
| DEP4313102.6 | 1993-04-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1994024484A1 true WO1994024484A1 (en) | 1994-10-27 |
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ID=6486058
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP1994/001101 Ceased WO1994024484A1 (en) | 1993-04-22 | 1994-04-09 | Method of reducing the emissions produced by incinerating waste |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5826521A (en) |
| EP (1) | EP0694147B1 (en) |
| DE (3) | DE4313102A1 (en) |
| WO (1) | WO1994024484A1 (en) |
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| US5309850A (en) * | 1992-11-18 | 1994-05-10 | The Babcock & Wilcox Company | Incineration of hazardous wastes using closed cycle combustion ash vitrification |
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- 1994-04-09 US US08/532,580 patent/US5826521A/en not_active Expired - Fee Related
- 1994-04-09 EP EP94913561A patent/EP0694147B1/en not_active Expired - Lifetime
- 1994-04-09 DE DE59403467T patent/DE59403467D1/en not_active Expired - Lifetime
- 1994-04-09 WO PCT/EP1994/001101 patent/WO1994024484A1/en not_active Ceased
- 1994-04-09 DE DE9414301U patent/DE9414301U1/en not_active Expired - Lifetime
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| JPS5348079A (en) * | 1976-10-14 | 1978-05-01 | Mitsui Eng & Shipbuild Co Ltd | Rotary kiln apparatus |
| JPS5924115A (en) * | 1982-08-02 | 1984-02-07 | Nippon Furnace Kogyo Kaisha Ltd | Combustion of powdered coal |
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| EP0495766A2 (en) * | 1991-01-14 | 1992-07-22 | TBR Gesellschaft f. techn. Bodenreinigung Ges.m.b.H. | Method for the utilization of residual material from pyrolysis and of pyrolysis gas |
| US5179903A (en) * | 1991-06-24 | 1993-01-19 | Abboud Harry I | Closed loop incineration process |
| DE4218628A1 (en) * | 1991-09-13 | 1993-03-18 | Zweckverband Sondermuellentsor | Environmentally protective rotary drum furnace - has warmed air from cooled end seals and leakage gases returned to combustion zone at feed end |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1107833A4 (en) * | 1998-04-06 | 2001-06-20 | Minergy Corp | Closed-cycle waste combustion |
| DE102015117718A1 (en) * | 2015-10-19 | 2017-04-20 | Karlsruher Institut für Technologie | Firing system and method for its operation |
| WO2017067540A1 (en) | 2015-10-19 | 2017-04-27 | Karlsruher Institut für Technologie | Firing system and method for operating same |
| FR3108160A1 (en) * | 2020-03-10 | 2021-09-17 | Vinci Environnement | HEAT PRODUCTION PROCESS FROM SOLID RECOVERY FUELS |
| LU103187B1 (en) * | 2023-08-21 | 2025-02-21 | Thyssenkrupp Ag | Safe preparation of fuels using the oxyfuel process |
| WO2025040528A1 (en) | 2023-08-21 | 2025-02-27 | thyssenkrupp Polysius GmbH | System for producing thermally activated materials |
Also Published As
| Publication number | Publication date |
|---|---|
| DE9414301U1 (en) | 1995-02-02 |
| DE59403467D1 (en) | 1997-08-28 |
| EP0694147A1 (en) | 1996-01-31 |
| DE4313102A1 (en) | 1994-10-27 |
| EP0694147B1 (en) | 1997-07-23 |
| US5826521A (en) | 1998-10-27 |
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